title: Longitudinal trends and influence of BMI mismatch in living kidney donors and their recipients.
abstract: OBJECTIVE
  Age and body mass index (BMI) of kidney donors and recipients affect kidney allograft outcomes. Moreover, while deceased donor and recipient body size mismatch have been reported to influence allograft outcomes, how BMI mismatch in living kidney donor-recipient pairs affect graft survival is not well defined.
  
  
  METHODS
  We investigated trends in characteristics of 90,815 US. living kidney donors and their recipients between 1987 and 2008.
  
  
  RESULTS
  Median ages of donors and their recipients have risen over time, and the proportion of living donors age ≥ 50 years increased from 11 to 25%. Median BMI of recipients increased from 22.6 to 26.6 kg/m(2); median BMI of kidney donors for the past 5 years has been 26.4 kg/m(2). Only 35% of living donor-recipient pairs were in the same BMI category (<25, 25-29.9, 30-34.9, or ≥ 35 kg/m(2)). BMI mismatch where the living donor was three categories heavier than the recipient was associated with a significant adjusted risk for death-censored allograft loss (HR 2.31, 95% CI 1.05-5.08).
  
  
  CONCLUSIONS
  Living kidney donors are donating at more advanced ages, and the majority are overweight or obese in recent years. In summary: (1) previous longitudinal studies of living kidney donor outcomes may not be generalizable to recent donors, and studies of contemporary living kidney donor cohorts may be informative, (2) the majority of living donor-recipient pairs have BMI mismatch, and (3) extreme BMI mismatch where the living donor is heavier may confer an independent risk for allograft loss.
authors.affiliation: Renal Division and Division of Transplantation Surgery, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. jlin11@partners.org
authors.forename: Julie
authors.initials: J
authors.lastname: Lin
authors.forename: Molly E
authors.initials: ME
authors.lastname: McGovern
authors.forename: Steven M
authors.initials: SM
authors.lastname: Brunelli
authors.forename: Peter
authors.initials: P
authors.lastname: Gaccione
authors.forename: Sayeed
authors.initials: S
authors.lastname: Malek
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Tullius
authors.forename: Anil K
authors.initials: AK
authors.lastname: Chandraker
authors.forename: Edgar L
authors.initials: EL
authors.lastname: Milford
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D016009:Chi-Square Distribution; D005260:Female; D006085:Graft Survival; D006801:Humans; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000208:ethnology / Q000639:trends*; D019520:Living Donors / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D014481:United States